Permselective membranes suitable for use in desalination of aqueous solutions are the subject of numerous patents. U.S. Pat. No. 4,719,062 discloses permselective multilayer membrane in which there is a microporous polysulfone substrate layer and a superposed polyamide layer made from an aromatic diamine and trimesoyl chloride or cyclohexane-1,3,5-tricarboxyl chloride optionally containing up to 50% of either terephthaloylchloride or isophthaloyl chloride. Cadotte U.S. Pat. No. 4,277,344 permselective multi-layer membranes in which there is a microporous polysulfone substrate layer and a superposed polyamide layer made from an aromatic triacid halide and an aromatic diamine. Scala et al. U.S. Pat. No. 3,744,642 discloses multilayer membranes in which one layer is a porous substrate and the juxtaposed layer is a polyamide, a polyphenylester, or a polysulfonamide. Weyland et al. U.S. Pat. No. 3,649,687 discloses the use of 1,3,5-cyclohexane tricarbonyl chloride in the production of crosslinking agent: 1,3,5-cyclohexane triisocyanate. U.S. Pat. Nos. 4,520,044 and 4,529,646 disclose permselective multilayer membranes in which there is a microporous polysulfone support and a polyamide layer made using 1,3,5-cyclohexane tricarbonyl chloride and a diamine.
U.S. Pat. No. 4,626,468 discloses permselective multilayer membranes in which there is a microporous polysulfone support and a polyamide layer made from meta-phenylenediamine and based on polymerized acid chloride present from 10 to 80 weight percent repeating units derived from trimesoyl chloride, 90 to 15 weight percent repeating units derived from cyclohexane-1,3,5-tricarbonyl chloride and up to 40 weight percent repeating units derived from isophthaloyl chloride, terephthaloyl chloride or mixtures thereof.
U.S. Pat. No. 4,783,346 discloses a multistage process for preparing interfacially polymerized polyamide reverse osmosis membranes on a microporous support. The process involves first applying a solution containing from 1 to 10 wt % of an aromatic diamine having 1 or 2 rings and then a solution of a mixture of acyl chlorides having a combined average per acyl chloride-containing molecule of 2.2 to 4 acyl chloride groups in a solvent immiscible with the first solvent applied to the microporous substrate. Then a solution of different acyl chlorides is applied to the substrate. The individual acyl chlorides in this second solution can have 2.2 to 4 acyl chloride groups attached to an alkylene aliphatic group of 4 to 12 carbon atoms or an aromatic or cycloaliphatic group having 1 or 2 rings and containing 6 to 14 carbon atoms.
U.S. Pat. No. 4,643,829 discloses a multilayer membrane for performing reverse osmosis comprising a porous support and a layer formed of poly(meta-phenylenecyclohexane-1,3,5-tricarboxamide).